(Press-News.org) Women using fertility drugs who did not conceive a 10-plus week pregnancy were at a statistically significant reduced risk of breast cancer compared to nonusers; however, women using the drugs who conceived a 10-plus week pregnancy had a statistically significant increased risk of breast cancer compared to unsuccessfully treated women, but a comparable risk to nonusers, according to a study published July 6 in the Journal of The National Cancer Institute.
Ovulation-stimulating fertility drugs temporarily elevate estrogen levels in women, and estrogen is known to play an important role in breast cancer. While some studies report increased breast cancer risk following infertility treatment, other analyses have been inconclusive.
In order to determine the risk of young-onset breast cancer after use of ovulation-stimulating fertility drugs, Chunyuan Fei, Ph.D., at the National Institute of Environmental Health Sciences (NIEHS), and colleagues, conducted a sister-matched case-control study, in part funded by Susan Komen for the Cure, called the Two Sister Study (which was developed from the Sister Study), which looked at women diagnosed with breast cancer under the age of 50 years and their breast cancer-free control sisters, who were studied between September 2008-December 2010. They looked specifically at fertility-drug exposure according to whether or not it had resulted in a pregnancy lasting at least 10 weeks.
The researchers found that women who had used fertility drugs showed a non-statistically significantly reduced risk of breast cancer compared to women who did not use fertility drugs and women who used fertility drugs and did not conceive a 10-plus week pregnancy were at a statistically significantly lowered risk of breast cancer compared to nonusers. Women who had used fertility drugs and conceived a 10-plus week pregnancy did, however, have a statistically significantly increased risk of breast cancer compared to women who had been unsuccessfully treated. "Our data suggest that exposure to a stimulated pregnancy is enough to undo the reduction in risk associated with a history of exposure to ovulation-stimulating drugs," the authors write. They believe the exposure to the fertility drugs potentially raises risk by modifying pregnancy-related remodeling of breast tissue. However, successfully treated women had a comparable level of breast cancer risk to non-users.
The authors note a few limitations of the study, including the reliance on self-reported fertility drug usage, and lack of data on specific diagnosis for infertility.
In an accompanying editorial, Louise A. Brinton, Ph.D., of the Division of Cancer Epidemiology and Genetics at the National Cancer Institute, feels that the findings of the study are hard to understand in the context of previous studies with results ranging from a lowered risk to a higher risk to no relationship between the drugs and the risk of early onset of breast cancer. Brinton explains that the reduced overall risk associated with drug usage may be related to the fact that one of the drugs, clomiphene, is a selective estrogen receptor modulator (SERM) similar to tamoxifen, an established chemo-preventative. On the other hand, increased risk seen in successfully treated women may be related to the increased exposure to ovarian hormones, as well as "the dual effect of pregnancy on breast cancer risk, namely a short-term transient increase that dissipates with time and eventually leads to a long-term risk reduction," Brinton writes. Another complicating factor in interpreting the study's results is its focus on women who developed breast cancer before age 50, which is more often associated with genetic factors than breast cancers diagnosed at a later age.
Brinton concludes that additional research is needed to understand these associations. "Because of such complexities, results from individual investigations must be cautiously interpreted and weighed against the considerable benefits associated with fertility drug usage, including a high probability of carrying pregnancies to term, which can lead to substantial long-term reductions in breast cancer risks."
INFORMATION:
Contact Info:
Article: NIEHS Office of Communications at arnetter@niehs.nih.gov ; 919-541-5143
Editorial: Louise A. Brinton, Ph.D., Brinton@nih.gov ; 301-496-1693
END
Cambridge, Mass. - July 6, 2012 - Atmospheric scientists at the Harvard School of Engineering and Applied Sciences (SEAS) and Nanjing University have produced the first "bottom-up" estimates of China's carbon dioxide (CO2) emissions, for 2005 to 2009, and the first statistically rigorous estimates of the uncertainties surrounding China's CO2 emissions.
The independent estimates, rooted in part in measurements of pollutants both at the sources and in the air, may be the most accurate totals to date. The resulting figures offer an unbiased basis on which China might measure ...
Professor Ian Simmonds from the University of Melbourne's School of Earth Sciences co-authored the study and said the new information showed this combined effect at both ground and atmospheric level played a key role in increasing the rate of warming in the Arctic.
"Loss of sea ice contributes to ground level warming while global warming intensifies atmospheric circulation and contributes to increased temperatures higher in the Arctic atmosphere," Professor Simmonds said.
Lead author, Dr James Screen of the School of Earth Sciences at the University of Melbourne said ...
These kinds of experiments are important as they reveal the interaction strength of the X-rays with the liquids and therefore allow for the structural analysis of substances dissolved in solution. "The method will achieve its absolute apprehension when will be applied to metal ions that are part of chemical catalysts used for clean energy production and biocatalysts (protein enzymes) used in biochemical transformation inside the living cells – the team leader Prof. Aziz stated, which is the next milestone in our research progress. Previously, these types of experiments ...
Research from the University of Southampton and National Oceanography, Southampton has provided new insight into the basic immune response and repair mechanisms of corals to disease and changing environmental conditions.
The study, published in the latest issue of the journal Coral Reefs, found that increased growth is the underlying physiological process associated with disease, wounding and stress-related colour changes in reef-building corals.
The study investigated distinct green fluorescent protein (GFP)-like pigments responsible for the green, red and purple-blue ...
A team of researchers from the Technical University of Valencia, the University Hospital La Fe, the University of Valencia and the Universitat Autònoma de Barcelona conducted in vitro studies of cytotoxicity (cellular affection) to assess the optimal concentration level of propolis in which this natural substance extracted from bee resin would offer the maximum protection against ionised radiation and not be toxic for blood cells.
According to the results of the research, this optimal concentration level is between 120-500 micrograms/mL. "Within this range can be found ...
The effect of spaceflight on a microscopic worm — Caenorhabditis elegans (C. elegans) — could help it to live longer.
The discovery was made by an international group of scientists studying the loss of bone and muscle mass experienced by astronauts after extended flights in space. The results of this research have been published today, July 5 2012, in the online journal Scientific Reports.
Dr Nathaniel Szewczyk, from The University of Nottingham, was part of the ICE-FIRST project which involved scientists from Japan, France, the US, and Canada. They discovered that ...
The University of Nottingham has begun the search for a new class of injectable materials that will stimulate stem cells to regenerate damaged tissue in degenerative and age related disorders of the bone, muscle and heart.
The work, which is currently at the experimental stage, could lead to treatments for diseases that currently have no cure. The aim is to produce radical new treatments that will reduce the need for invasive surgery, optimise recovery and reduce the risk of undesirable scar tissue.
The research, which brings together expertise in The University of ...
Bethesda, MD—A new research report published online in the FASEB Journal reveals a connection among sugar, cancer, and dependence on breathing machines--microRNA-320a. In the report, Stanford scientists show that the molecule microRNA-320a is responsible for helping control glycolysis. Glycolysis is the process of converting sugar into energy, which fuels the growth of some cancers, and contributes to the wasting of unused muscles such as the diaphragm when people are using ventilators. Identifying ways to use microRNA-320a to starve tumors and keep unused muscles strong ...
London (July 05 2012 ) -- European experts in cardiovascular medicine will today gather at a two day symposium to address the national agenda on cardiovascular disease prevention, held at Imperial College London and sponsored by leading independent academic and professional publisher SAGE.
One session at the conference, chaired by Professors Joep Perk and David Wood will focus on the new 2012 Joint European Societies' Guidelines on cardiovascular disease prevention in clinical practice, which will appear in August issue (volume 19, issue 4) of the European Society of ...
Feelings of anxiety very effectively prevent people from getting into situations that are too dangerous. Those who have had a terrible experience initially tend to avoid the place of tragedy out of fear. If no other oppressive situation arises, normally the symptoms of fear gradually subside. "The memory of the terrible events is not just erased." states first author, PD Dr. Andras Bilkei Gorzo, from the Institute for Molecular Psychiatry at the University of Bonn. "Those impacted learn rather via an active learning process that they no longer need to be afraid because ...
